1. Field of the Invention
The present invention relates to an apparatus for cleaning the interior of tubes used in heat exchanger bundles. More particularly, the present invention relates to an apparatus capable of simultaneously cleaning the interior of several curved tubes within a heat exchanger bundle on site.
2. Description of the Prior Art
Heat exchanger tube bundles are used for the transfer of heat from a fluid media passing through a series of conduits. During this process, carbonaceous and calcareous deposits will form on the interior of the individual tubes and debris and other dirt will collect on the surface of the individual tubes. Therefore, in order to maintain efficient operation, it is necessary to periodically remove the tube bundles and clean the interior and exterior of the tubes.
One method of cleaning the interior of heat exchanger tubes includes the progressive insertion of a small diameter tube, known as a lance, into the heat exchanger tube and pumping high pressure water through the lance to clean the interior of the tube. The water pressure in a lance may easily exceed 10,000 psi and flow rates in excess of 100 gallons per minute. Prior art devices called for the lance to be manually operated and advanced into the exchanger tube. It will be appreciated that the manual operation of a lance is unsatisfactory for a number of reasons. First, the operator is required to overcome the force of the water pressure when inserting the lance into the tube. Further, should the lance wall rupture, an operator may be injured by the high pressure water flow. Similarly, an operator may be injured by back-splash from the lance during the insertion of the lance in the tube. Lastly, the manual operation of a lance is time consuming and costly as only one lance may be used in manual operations.
Various mechanical devices have been used in an effort to overcome the above deficiencies in cleaning the interior of heat exchanger tubes. U.S. Pat. No. 3,903,912 to Ice, et al. discloses a multiple lance cleaning system, including lance positioning and drive means and exposed lance tubes. However, the use of exposed lance tubes continues to pose a danger to an operator should a lance wall rupture. U.S. Pat. No. 3,817,262 to Cradeur also discloses a multiple lance cleaning system having a lance positioner and drive system and exposed lance tubes. However, as in the Ice disclosure, the operator is still exposed to the danger of potential lance tube rupture.
U.S. Pat. No. 3,901,252 to Riebe discloses a multiple lance system including a lance drive and enclosed lance tubes, manifold and water lines. However, Riebe does not disclose a lance positioning system capable of readily positioning the lances and lance drive into a multitude of tubes within the heat exchanger bundle nor does it disclose a system for retracting the water pressure line. U.S. Pat. No. 4,856,545 to Krajicek disclosed a multi-lance tube cleaning system having a lance drive means, lance tubes and manifold and multiple high pressure water lines within an enclosed structure. The disclosure called for the cleaning structure to be positioned by a crane mounted on a truck or by other mobile crane, tractor or skid. However, there are a number of disadvantages, i.e., as the lances are moved forward the center of gravity of the structure may shift which could result in misalignment and unnecessary stress on the lance tubes.
Further, none of the above devices disclose a means for cleaning tubes wherein the tubes are arranged in a curved path. All of the above disclose a rigid lance incapable of traversing a curved path. A heat exchanger tube may follow a serpentine or other curved path. One example of a curved path includes inter-tube connections, such as U shaped connectors which permit flow between various tubes within the heat exchanger bundle.
Accordingly, there exists a need for an improved tube bundle cleaner having enclosed tube lances, the lances being capable of traversing a curved path, means for transporting water to the lances and for accurately supporting and positioning the lances during operation, and means for retracting the water pressure line in an efficient and thorough manner. While there are other disclosures directed to the cleaning of the interior of heat exchanger bundles (such as U.S. Pat. Nos. 3,589,388; 2,494,380; 1,694,371; and 620,224), none disclose or suggest a multi-lance cleaning system having enclosed lances capable of traversing a curved path, manifold and an independent means for positioning the lance cleaning system.